1. Technical Field
Embodiments of the present invention relate to an injection mold and an injection molding method using the same.
2. Description of the Related Art
A conventional injection mold that may be used to produce plastic molded parts may include a cavity plate and a core plate having cavities. There are generally two main types of conventional injection molds. One is a two-plate injection mold, and the other is a three-plate injection mold.
A two-plate injection mold has a parting plane positioned between a cavity plate and a core plate. When the injection mold is opened, injection-molded parts may be removed therefrom. However, gate molded parts, formed by resin that hardens in gates of a conventional mold, are also attached to injection-molded parts that are removed from the two-plate injection mold. Thus, an additional process is required to separate the gate molded parts from the injection-molded parts.
Unlike a two-plate injection mold, a three-plate injection mold includes a stripper plate disposed between a cavity plate and an upper clamp plate. The stripper plate causes the three-plate injection mold to have two parting planes. Thus, gate molded parts can be separated from injection-molded parts within the three-plate injection mold. Accordingly, pinpoint gates can be used in a three-plate injection mold.
Since a two-plate injection mold has a simple structure, it can use extension cylinders. Extension cylinders extend into a two-plate injection mold, and molten resin that is injected into the two-plate injection mold flows through the extension cylinders while being kept in a molten state. Unlike a two-plate injection mold, a three-plate injection mold further includes lock pins coupled to an upper clamp plate and a stripper plate disposed under the upper clamp plate. A three-plate injection mold has a more complex structure than a two-plate injection mold, and thus it is difficult to install extension cylinders within the three-plate injection mold. Accordingly, resin that is fed into a three-plate injection mold hardens as it flows through runners within the three-plate injection mold. Generally, a large amount of hardened resin is formed when a three-plate injection mold is used, and this hardened resin is then usually thrown away as waste.
Currently, three-plate injection molds having pinpoint gates are being used to produce light-emitting diode (LED) lead frames. However, as described above, since conventional three-plate injection molds cannot have extension cylinders therein, a large amount of resin is thrown away. The amount of resin that is thrown away accounts for 90% or more of the total amount of resin that is injected into a three-plate injection mold to produce lead frames.